Riluzole, an active pharmaceutical ingredient that has a very low solubility in water (i.e., about 0.3 mg/mL at neutral pH), is used to treat amyotrophic lateral sclerosis (ALS). Currently, the only FDA-approved dosage form of riluzole is an oral tablet, which is usually administered at a dose of 50 mg every 12 hours to delay the onset of ventilator-dependence or tracheostomy. An increased rate of adverse events including dizziness, diarrhea, and anorexia prevent higher doses of riluzole from being administered orally. Accordingly, there remains a need in the art for alternative treatment regimens that have an improved safety profile.